Receiving apparatus and receiving method

ABSTRACT

Determination section  107  determines whether a control channel is intended for a reception apparatus having the determination section  107 , and when it is determined that the control channel is intended for the reception apparatus, capability comparing section  113  compares control information transmitted on the control channel with the reception capability of the reception apparatus. Data channel reception section  108  receives a data channel when the control information is within a scope of the reception capability of the reception apparatus, while not receiving the data channel when the control information is out of a scope of the reception capability of the reception apparatus. Further, when the control information is out of the scope of the reception capability of the reception apparatus, transmission section  112  does not transmit an ACK signal and NACK signal in response to the data channel.

TECHNICAL FIELD

The present invention relates to a reception apparatus and receptionmethod using control information transmitted on a control channel indecoding information data transmitted on a data channel.

BACKGROUND ART

FIG. 1 is a diagram illustrating control channels transmitted from atransmission apparatus. In the figure, the control channels are used intransmitting information necessary for performing reception,demodulation and decoding on a data channel i.e. control informationincluding the number of multicodes, modulation scheme, the number ofinformation bits, and so on. When there are a plurality of receptionapparatuses, information indicating which reception apparatus thechannel is for is coded and transmitted on each control channel, so thateach reception apparatus is able to detect the control channel for thereception apparatus from among multiple received control channels.

FIG. 2 is a block diagram illustrating a configuration of a conventionalreception apparatus. Reception apparatus 8 as shown in the figure isprovided with antenna 9, duplexer 10, reception section 11, controlchannel reception section 12, control channel demodulation section 13,control channel decoding section 14, determination section 15, controlsection 16, data channel reception section 17, data channel demodulationsection 18, data channel decoding section 19, error detection section 20and transmission section 21. In such a configuration, signals of aplurality of (or a single) control channels are received in antenna 9,output to duplexer 10 and reception section 11 sequentially, andreceived in control channel reception section 12. The received signalsof the plurality of control channels are input to control channeldemodulation section 13, and subjected to demodulation for each channel.Each demodulation result is input to control channel decoding section14. Control channel decoding section 14 performs decoding on thedemodulation result of each of the plurality of control channels inputfrom control channel demodulation section 13, and inputs the decodingresults to determination section 15.

Based on each of the decoding results input from control channeldecoding section 14, determination section 15 determines whether thereis a channel intended for reception apparatus 8 among the receivedplurality of control channels. The determination is made, for example,using an error check bit and/or likelihood information calculated incontrol channel decoding section 14. When a control channel forreception apparatus 8 is present as a result of the determination,determination section 15 notifies control section 16 of the presence.Upon receiving the notification, control section 16 controls datachannel reception section 17, data channel demodulation section 18, anddata channel decoding section 19 to perform reception, demodulation anddecoding on a data channel using control information indicated by thedecoding result of the control channel for reception apparatus 8.

Meanwhile, error detection section 20 detects an error of decoded datainput from data channel decoding section 19, and notifies controlsection 16 of the result. In the case of receiving the notificationindicating that no error is detected from error detection section 20,control section 16 outputs an ACK (ACknowledgment) signal to transmitfrom transmission section 21. In the case of receiving the notificationindicating that an error is detected from error detection section 20,control section 16 outputs a NACK (Negative ACknowledgment) signal totransmit from transmission section 21. Further, in the case where acontrol channel for reception apparatus 8 is not detected from adetermination result in determination section 15, control section 16does not perform reception of data channel.

In addition, a method is proposed that reception processing on a datachannel is controlled using an error detecting code of controlinformation added to the data channel in receiving the data channel (forexample, Japanese Laid-Open Patent Publication 2000-244463).

However, conventional reception apparatus 8 as described above has sucha problem that when the control channel determination misidentifies acontrol channel not for reception apparatus 8 as a control channel forreception apparatus 8, reception, demodulation and decoding on a datachannel is carried out using wrong control information.

Further, when data channel signals are properly decoded accidentallyusing wrong control information, data to a reception apparatus exceptreception apparatus 8 is received, and there arise problems withinconsistency of data and confidentiality.

Furthermore, in a communication system using so-called hybrid ARQ(Automatic Repeat reQuest), when reception, demodulation and decoding ona data channel is once carried out using wrong control information, itis not possible to decode data accurately in error correction usingsubsequent retransmitted data, and gains in hybrid ARQ may be lost as aresult.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a receptionapparatus and reception method capable of preventing execution ofreception, demodulation and decoding on a data channel using wrongcontrol information.

In order to achieve the object, in the present invention, whether or nota received control channel is intended for a reception apparatus havingreceived the channel is determined using an error checkbit, likelihoodinformation calculated in decoding the control channel, or the like.Then, when it is determined that the control channel is intended for thereception apparatus, the apparatus compares control information (thenumber of multicodes, modulation scheme, the number of information bitsand so on necessary for reception of a data channel) transmitted on thecontrol channel with the reception capability (the number of multicodes,modulation scheme, the number of information bits and so on available inthe reception apparatus) of the reception apparatus, and does notreceive the data channel unless the control information is within ascope of the reception capability of the reception apparatus. Meanwhile,when the control information is within the scope of the receptioncapability, the data channel is received.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a chart to explain a structure of a control channel;

FIG. 2 is a block diagram illustrating a configuration of a conventionalreception apparatus;

FIG. 3 is a block diagram illustrating a configuration of a receptionapparatus according to one embodiment of the present invention;

FIG. 4 is a chart illustrating a frame structure of HS-PDSCH used in anHSDPA system;

FIG. 5 is a chart illustrating a frame structure of HS-SCCH used in theHSDPA system; and

FIG. 6 is a chart illustrating a timing relation between HS-SCCH andHS-PDSCH.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be specifically describedbelow with reference to accompanying drawings.

FIG. 3 is a block diagram illustrating a configuration of a receptionapparatus according to one embodiment of the present invention. In FIG.3, reception apparatus 100 according to this embodiment has capabilitycomparing section 113. When determination section 107 determines thereis a control channel intended for reception apparatus 100, the section113 compares control information transmitted on the control channel withthe reception capability of reception apparatus 100 to check reliabilityof the determination about the control channel that is determined to befor reception apparatus 100. Reception apparatus 100 further has controlsection 114. The section 114 does not receive a data channel nor performtransmission of an ACK signal and NACK signal unless the controlinformation is within a scope of the reception capability of receptionapparatus 100 in the comparison in capability comparing section 113,while receiving a data channel and transmitting an ACK signal or NACKsignal when the control information is within the scope of the receptioncapability of reception apparatus 100.

Control channel reception section 104 receives signals of a plurality of(or a single) control channels from radio signals received in receptionsection 103 via duplexer 102, and inputs each of the received pluralityof control channels to control channel demodulation section 105. Controlchannel demodulation section 105 performs demodulation on each of theplurality of control channels input from control channel receptionsection 104, and inputs each demodulation result to control channeldecoding section 106. Control channel decoding section 106 performsdecoding on respective demodulation results of the plurality of controlchannels input from control channel demodulation section 105, and inputseach decoding result to determination section 107.

Determination section 107 determines whether there is a control channelintended for reception apparatus 100 among the received plurality ofcontrol channels from respective decoding results of the plurality ofcontrol channels, and notifies the determination result to controlsection 114. When determination section 107 determines that a controlchannel intended for reception apparatus 100 exists and notifies thedetermination result to control section 114, control section 114instructs control channel decoding section 106 to output controlinformation that is a decoding result of the control channel forreception apparatus 100 to capability comparing section 113. Capabilitycomparing section 113 compares the control information input fromcontrol channel decoding section 106 with the reception capability ofreception apparatus 100, and notifies the comparison result to controlsection 114. Corresponding to outputs from determination section 107 andcapability comparing section 113, control section 114 controls controlchannel decoding section 106 and data channel reception section 108.

According to the instruction from control section 114, data channelreception section 108 receives a data channel using the controlinformation obtained by decoding the control channel. Data channeldemodulation section 109 performs demodulation on the data channel usingthe control information obtained by decoding the control channel. Datachannel decoding section 110 performs decoding on the data channel usingthe control information obtained by decoding the control channel, andoutputs decoded data. Error detection section 111 detects an error ofthe decoded data input from data channel decoding section 110, andnotifies the result to control section 114. When receiving anotification indicative of no error being detected from error detectionsection 111, control section 114 outputs an ACK signal to transmissionsection 112. Meanwhile, when receiving a notification indicative of anerror being detected from error detection section 111, control section114 outputs a NACK signal to transmission section 112. In addition,control section 114 controls whether or not to transmit the ACK signalor NACK signal according to the comparison result in capabilitycomparing section 113. Transmission section 112 transmits the ACK signaland NACK signal output from control section 114.

The operation of reception apparatus 100 according to this embodimentwill be described below. First, a plurality of control channelstransmitted from a transmission apparatus is received in control channelreception section 104. The received plurality of control channels aredemodulated in control channel demodulation section 105, and decoded incontrol channel decoding section 106. Then, decoding results of theplurality of control channels are input to determination section 107.

At this point, when the transmission apparatus transmits a controlchannel addressed to reception apparatus 100, it is required to detectthe channel for reception apparatus 100 among the received plurality ofcontrol channels. When the transmission apparatus does not transmit acontrol channel addressed to reception apparatus 100, it is required notto detect a wrong control channel.

Therefore, when an error check bit is added to a control channel,determination section 107 determines whether each of the plurality ofcontrol channels is a control channel intended for reception apparatus100 using the error check bit. In contrast thereto, when an error checkbit is not added to a control channel, determination section 107determines whether each of the plurality of control channels is acontrol channel intended for reception apparatus 100, using outputlikelihood of a Viterbi decoder, turbo decoder or the like used indecoding in control channel decoding section 106. Then, determinationsection 107 inputs the determination result to control section 114.

When recognizing that there is no control channel intended for receptionapparatus 100 from the determination result, control section 114instructs data channel reception section 108 to discard a data channelwithout performing reception on the data channel. In contrast thereto,when recognizing that there is a control channel intended for receptionapparatus 100 from the determination result, reception apparatus 100compares control information (the number of multicodes, modulationscheme and the number of information bits necessary for reception of thedata channel) transmitted on the control channel determined to be forreception apparatus 100 with the reception capability (the number ofmulticodes, modulation scheme and the number of information bitsavailable in reception apparatus 100) of reception apparatus 100. Inother words, control section 114 instructs capability comparing section113 to compare the control information that is the decoding result ofthe control channel determined to be for reception apparatus 100 withthe reception capability of reception apparatus 100.

When it is recognized from the comparison result output from capabilitycomparing section 113 that the control information transmitted on thecontrol channel determined to be for reception apparatus 100 is within ascope of the reception capability of reception apparatus 100, controlsection 114 instructs data channel reception section 108 to receive thedata channel. Meanwhile, when the control information transmitted on thecontrol channel determined to be for reception apparatus 100 is out ofthe scope of the reception capability of reception apparatus 100,control section 114 instructs data channel reception section 108 not toreceive the data channel.

For example, it is assumed herein that the reception capability ofreception apparatus 100 is of five codes as the number of multicodes,and that the control information transmitted on the control channeldetermined to be for reception apparatus 100 indicates five codes as thenumber of multicodes. In this case, the number of multicodes indicatedin the control information is not more than the number of multicodesthat reception apparatus 100 is capable of receiving, the controlinformation is thus within a scope of the reception capability ofreception apparatus 100, and therefore, control section 114 instructsdata channel reception section 108 to receive the data channel.

It is further assumed that the control information transmitted on thecontrol channel determined to be for reception apparatus 100 indicatesten codes as the number of multicodes. In this case, the number ofmulticodes indicated in the control information exceeds the number ofmulticodes that reception apparatus 100 is capable of receiving, and thecontrol information is thus out of the scope of the reception capabilityof reception apparatus 100. Therefore, control section 114 determinesthat the control channel was erroneously determined to be for receptionapparatus 100 in determination section 107, and instructs data channelreception section 108 not to receive this data channel. At this point,there is a possibility that another reception apparatus transmits asignal to the transmission apparatus at the timing at which receptionapparatus 100 transmits an ACK signal or NACK signal, and therefore,reception apparatus 100 does not transmit the ACK signal or NACK signal.In other words, when the control information is out of a scope of thereception capability of reception apparatus 100, control section 114instructs transmission section 112 not to transmit the ACK signal orNACK signal. According to this instruction, when the control informationis out of a scope of the reception capability of reception apparatus100, transmission section 112 does not transmit the ACK signal or NACKsignal. By this means, it is possible to suppress interference providedto signals transmitted from another reception apparatus.

A case will be descried below where reception apparatus 100 according tothis embodiment is applied to an HSDPA (High Speed Downlink PacketAccess) system based on specifications of 3GPP (3rd GenerationPartnership Project) that is a standardization project in mobilecommunications.

FIG. 4 is a chart illustrating a frame structure of HS-PDSCH (HighSpeed-Physical Downlink Shared Channel) used in the HSDPA system. FIG. 5is a chart illustrating a frame structure of HS-SCCH (High Speed-SharedControl Channel) used in the HSDPA system. As shown in FIG. 4, HS-PDSCHthat is a physical channel is comprised of a subframe having three slots(slots #0 to #2), and is a data channel including information bits.Further, as shown in FIG. 5, HS-SCCH that is a physical channel is acontrol channel comprised of a subframe having total three slots, slot#0 that is a first part, and slots #1 and #2 that are a second part. Thefirst part includes information indicative of a channelization codenumber, the number of channelization codes, and a modulation scheme usedin HS-PDSCH, and the second part includes a transport block size, ahybrid ARQ process number, hybrid ARQ parameter and new dataidentification bit. The information included in the first and secondparts of HS-SCCH is control information required for receptionprocessing of HS-PDSCH. In addition, the subframe length is 2 ms both inHS-PDSCH and HS-SCCH.

FIG. 6 is a chart illustrating the timing relation between HS-SCCH andHS-PDSCH. The beginning of the subframe of HS-SCCH is positioned twoslots earlier than the beginning of the subframe of correspondingHS-PDSCH. Since on HS-SCCH is transmitted coded information indicativeof a reception apparatus to which the HS-SCCH is transmitted, receptionapparatus 100 as shown in FIG. 3 detects HS-SCCH addressed to receptionapparatus 100 from a received plurality of HS-SCCHs. Then, using thecontrol information transmitted on the detected HS-SCCH, receptionapparatus 100 performs reception processing on HS-PDSCH. Since the firstpart and second part are separately coded on HS-SCCH, it is alsopossible to perform reception processing on HS-PDSCH using a decodingresult of the first part before finishing decoding of the second part.

With reference to FIG. 3, the operation will be described below ofreceiving the first part of HS-SCCH in reception apparatus 100 as shownin FIG. 3. Each of a plurality of HS-SCCHs transmitted from atransmission apparatus is received in control channel reception section104. Each of the received plurality of HS-SCCHs is demodulated incontrol channel demodulation section 105, and decoded in control channeldecoding section 106. Then, decoding results of the plurality ofHS-SCCHs is input to determination section 107.

At this point, when the transmission apparatus transmits HS-SCCHaddressed to reception apparatus 100, it is required to detect theHS-SCCH for reception apparatus 100 among the received plurality ofHS-SCCHs. When the transmission apparatus does not transmit HS-SCCHaddressed to reception apparatus 100, it is required not to detect wrongHS-SCCH.

Since an error check bit is not added to the first part of HS-SCCH,determination section 107 determines whether each of the plurality ofHS-SCCHs is a control channel intended for reception apparatus 100,using output likelihood of a Viterbi decoder used in decoding in controlchannel decoding section 106, and outputs the determination result tocontrol section 114.

When recognizing that there is no HS-SCCH for intended receptionapparatus 100 from the determination result, control section 114instructs data channel reception section 108 to discard HS-PDSCH withoutperforming reception on the HS-PDSCH. In contrast thereto, whenrecognizing that there is HS-SCCH intended for reception apparatus 100from the determination result, reception apparatus 100 compares controlinformation transmitted on the HS-SCCH determined to be for receptionapparatus 100 with the reception capability of reception apparatus 100.In other words, control section 114 instructs capability comparingsection 113 to compare the control information that is the decodingresult of the HS-SCCH determined to be for reception apparatus 100 withthe reception capability of reception apparatus 100. According to theinstruction from control section 114, capability comparing section 113compares the reception capability of reception apparatus 100 with achannelization code number, the number of channelization codes and amodulation scheme which are used in receiving HS-PDSCH corresponding tothe HS-SCCH determined to be for reception apparatus 100 and which arecontained in the first part of the HS-SCCH.

When it is recognized from the comparison result output from capabilitycomparing section 113 that the control information transmitted on theHS-SCCH determined to be for reception apparatus 100 is within a scopeof the reception capability of reception apparatus 100, control section114 instructs data channel reception section 108 to receive theHS-PDSCH. Meanwhile, when the control information transmitted on theHS-SCCH determined to be for reception apparatus 100 is out of the scopeof the reception capability of reception apparatus 100, control section114 instructs data channel reception section 108 not to receive theHS-PDSCH.

For example, it is assumed herein that the reception capability ofreception apparatus 100 is of ten codes as the number of multicodes ofHS-PDSCH, and that the control information transmitted on the HS-SCCHdetermined to be for reception apparatus 100 indicates five codes as thenumber of multicodes. In this case, the number of multicodes indicatedin the control information is less than the number of multicodes thatreception apparatus 100 is capable of receiving, the control informationis thus within a scope of the reception capability of receptionapparatus 100, and therefore, control section 114 instructs data channelreception section 108 to receive the HS-PDSCH.

It is further assumed that the control information transmitted on thecontrol channel determined to be for reception apparatus 100 indicatesfifteen codes as the number of multicodes. In this case, the number ofmulticodes indicated in the control information exceeds the number ofmulticodes that reception apparatus 100 is capable of receiving, and thecontrol information is thus out of the scope of the reception capabilityof reception apparatus 100. Therefore, control section 114 determinesthat the HS-SCCH was erroneously determined to be for receptionapparatus 100 in determination section 107, and instructs data channelreception section 108 not to receive the HS-PDSCH.

It is further assumed that a demodulation scheme on HS-PDSCH as thereception capability of reception apparatus 100 corresponds to onlyQPSK, and that the control information transmitted on HS-SCCH determinedto be for reception apparatus 100 indicates QPSK as a modulation scheme.In this case, since the modulation scheme indicated in the controlinformation agrees with the modulation scheme that reception apparatus100 is capable of receiving, the control information is within a scopeof the reception capability, and therefore, control section 114instructs data channel reception section 108 to receive the HS-PDSCH.

It is further assumed that the control information transmitted on acontrol channel determined to be for reception apparatus 100 indicates16QAM as a modulation scheme. In this case, the modulation schemeindicated in the control information does not agree with the modulationscheme that reception apparatus 100 is capable of receiving, and thecontrol information is thus out of the scope of the reception capabilityof reception apparatus 100. Therefore, control section 114 determinesthat the HS-SCCH was erroneously determined to be for receptionapparatus 100 in determination section 107, and instructs data channelreception section 108 not to receive the HS-PDSCH.

In this way, according to the reception apparatus of the presentinvention, by comparing the reception capability of the receptionapparatus with control information transmitted on a control channeladdressed to the reception apparatus among a plurality of controlchannels, it is possible to detect a control channel to the receptionapparatus with accuracy and prevent a data channel from being received,demodulated and decoded using wrong control information. Further, sincean ACK signal or NACK signal is not transmitted in this case, it ispossible to reduce interference on an other reception apparatus causedby transmission of the ACK signal or NACK signal.

In addition, in this embodiment, after determination section 107determines whether or not a received control channel is one intended forthe reception apparatus, capability comparing section 113 compares thecontrol information with the reception capability of the receptionapparatus. However, determination section 107 may determine whether ornot a received control channel is one intended for the receptionapparatus, after capability comparing section 113 compares the controlinformation with the reception capability of the reception apparatus.

As described above, according to the present invention, when a controlchannel addressed to a reception apparatus is detected, controlinformation transmitted on the control channel is compared with thereception capability of the reception apparatus, and it is therebypossible to prevent a data channel from being received, demodulated anddecoded using wrong control information. Further, since an ACK signal orNACK signal is not transmitted at this point, it is also possible toreduce interference on another reception apparatus caused bytransmission of the ACK signal or NACK signal.

This application is based on the Japanese Patent Application No.2003-034201 filed on Feb. 12, 2003, entire content of which is expresslyincorporated by reference herein.

Industrial Applicability

The present invention is applicable to a radio communication mobilestation apparatus used in a mobile communication system.

1. A reception apparatus comprising: a receiver that receives a controlchannel including control information and a data channel; a comparatorthat compares the control information with a reception capability of thereception apparatus; a detector that performs error detection on adecoding result of the data channel; a transmitter that transmits an ACKsignal or a NACK signal according to a detection result in the detector;and a controller that makes the transmitter transmit neither the ACKsignal nor the NACK signal when the control information is out of ascope of the reception capability of the reception apparatus.
 2. Thereception apparatus according to claim 1, further comprising: adeterminer that determines whether or not the control channel is acontrol channel intended for the reception apparatus, wherein thecontroller makes the transmitter transmit the ACK signal or the NACKsignal, when the control channel is a control channel intended for thereception apparatus and the control information is within the scope ofthe reception capability of the reception apparatus.
 3. The receptionapparatus according to claim 1, wherein the controller makes thereceiver receive the data channel using the control information.
 4. Thereception apparatus according to claim 1, wherein the control channel isHS-SCCH, while the data channel is HS-PDSCH.
 5. The reception apparatusaccording to claim 1, wherein when the number of multicodes required toreceive the data channel indicated in the control information exceedsthe number of multicodes that the reception apparatus is capable ofhandling the controller determines that the control information is outof the scope of the reception capability of the reception apparatus. 6.The reception apparatus according to claim 1, wherein when a modulationscheme used in transmitting the data channel indicated in the controlinformation is a modulation scheme that the reception apparatus is notcapable of handling, it is determined that the control information isout of the scope of the reception capability of the apparatus.
 7. Aradio communication mobile station apparatus comprising the receptionapparatus according to claim
 1. 8. A radio communication method used ina radio mobile station apparatus that receives a data channel usingcontrol information transmitted on a control channel, wherein when thecontrol channel is a control channel intended for the radio mobilestation apparatus and the control information is within a scope of areception capability of the radio mobile station apparatus, an ACKsignal or a NACK signal is transmitted based on an error detectionresult of the data channel.